1. Field of the Invention
The present invention relates to a method of driving a light source, a light source apparatus for performing the method and a display apparatus having the light source apparatus. More particularly, the present invention relates to a method of driving a light source which substantially improves a display quality, a light source apparatus for performing the method, and a display apparatus having the light source apparatus.
2. Description of the Related Art
Generally, a liquid crystal display (“LCD”) apparatus includes an LCD panel that displays images by controlling a transmittance of light through liquid crystal molecules, and a backlight unit disposed under the LCD panel to provide the LCD panel with light.
The LCD panel typically includes an array substrate, a color filter substrate and a liquid crystal layer interposed between the array substrate and the color filter substrate. The array substrate includes pixel electrodes and corresponding thin-film transistors (“TFTs”) electrically connected to the pixel electrodes. The color filter substrate includes a common electrode and a plurality of color filters.
When an electric field is applied to the liquid crystal layer, an alignment direction of the liquid crystal molecules in the liquid crystal layer is changed so that the transmittance of light therethrough is changed. For example, when the transmittance is at a maximum, the LCD panel displays a white image having a high luminance. In contrast, when the transmittance is at a minimum, the LCD panel displays a black image having a relatively low luminance.
Recently, in efforts to prevent a contrast ratio (“CR”) of an image from decreasing, as well as to minimize power consumption, a local dimming method for a light source in the LCD apparatus has been developed. In the local dimming method, the light source is divided into a plurality of light-emitting blocks and an amount of the light from each of the light-emitting blocks is controlled based on a luminance of an image corresponding to each of the light-emitting blocks.
In addition, various local dimming modes have been developed for the driving blocks. For example, in a global-dimming mode, s an entire screen is dimmed as a driving block, while in a one-dimensional dimming mode the driving block is divided with respect to longitudinal and/or latitudinal directions, and the divided blocks are then driven.
In a two-dimensional dimming mode, the driving block is divided with respect to both the longitudinal and the latitudinal directions and the divided blocks are then driven, while in a three-way dimming mode, color information is used in addition to positional information, and the luminance of a specific image is boosted in attempts to maximize image sensitivity by applying adaptive luminance and power control (“ALPC”) and other methods.
However, since the above-mentioned local dimming modes have limitations which include, but are not limited to, a requirement to drive the LCD apparatus block by block, a flickering phenomenon is generated when subtitles appear displayed images, such as in a movie. Specifically, in the global dimming mode and the boosting mode, the whole screen becomes dim or, alternatively, boosted when driving the LCD apparatus, and thus the flickering phenomenon is also generated by luminance differences between frames. In addition, in the one-dimensional dimming mode, luminance differences between blocks within a single frame are visible since a number of the blocks is relatively low compared to some other local dimming modes. Further, in the two-dimensional dimming mode, the flickering phenomenon is also generated, as is a glaring of the image, because of luminance differences between the block including the subtitles and other blocks.
However, in previous attempts to mitigate the above-mentioned deficiencies, when a number of driving blocks is increased to prevent generation of the flickering phenomenon due to the subtitles, for example, size and power requirements of a driving integrated circuit (“IC”) are substantially increased. Therefore, increasing the number of driving blocks is not desirable for the global dimming mode, or the one-dimensional dimming mode, for that matter, even though these methods are generally utilized in LCD apparatuses including edge-illumination type backlights. Thus, the flickering phenomenon is not effectively prevented in such an LCD apparatus utilizing the global dimming mode and/or the boosting mode.